Generation Y is synonymous with hookup culture.

And it's easy to see why: Fewer Millennials are in committed relationships than any generation in American history (Gallup, Pew).

But, according to multiple studies, millennials have fewer sexual partners than any generation since our grandparents, who averaged just two partners each at the same age.

So contrary to popular belief, the majority of Millennials are not having rampant, or even frequent, casual sex.

For those of us who aren't married and aren't having prolific sex, what are we doing?

Trying to decide.

By producing a surplus of options, online dating has ironically yielded romantic standstills.

Earlier this year, Pew Research Center found that one in five adults between 25-34 years old has used online dating. Ninety percent of Tinder's users, for example, are Millennials.

It's no wonder we're pegged as the hookup generation—these tools should make that easy!

But despite common usage among Millennials (Tinder boasts 26 million matches a day), online dating frequently never progresses offline—let alone to the bedroom. Pew surveys reveal that a third of online daters have never actually gone out with someone they met online.

There are lots of reasons online dating isn't fruitful (for example, many online daters lie on their profiles; online daters tend to be more shallow and predict their actual preferences poorly). But more limiting than all these obstacles is our own indecisiveness.

Research has repeatedly found that, despite our idealization of choice, we actually dislike too much of it. When overwhelmed with options, we tend to regret our decisions, obsess over foregone alternatives or simply not choose at all.

Online dating is no exception. PJ Vogt, a radio producer interviewed on a Freakonomics podcast, explained, "the hardest part [of online dating] is seeing all the people who seem pretty good."

The more options we see, the more we fear we'll choose the wrong one—what Priya Parker calls FOBO: Fear of Better Options. Vogt ultimately concluded, "I'd be so much happier...if I had almost no choice, and I could meet just one person and feel like I'd be happy with them."

This is especially true considering our shallow, self-sabotaging instincts when faced with endless options. In one study, the more potential partners people met while speed-dating, the more likely participants were to judge them more superficially.

Our option-induced worry that we'll choose the wrong one may also contribute to the notable lack of resiliency in relationships that began online. Though 70 percent of online daters believe these services help people find better matches, couples who do meet online are actually more likely to break up than couples who meet offline.

Yet, despite our inability to land and keep relationships, we want them. According to Pew's data, 61 percent of Millennials who have never married would like to someday. Similarly, eight in 10 Millennials say that true romance is "very important".

The solution to our indecisiveness may be unromantic. Author and economist Paul Oyer suggests the last thing our generation wants to do: settle. "Just as everybody accepts a job that doesn't have that last little perk they wanted, at some point you have to accept a life partner."

Our difficulty dating is self-inflicted—and the solution is at our fingertips.